| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Permission is hereby granted, free of charge, to any person |
| * obtaining a copy of this software and associated documentation |
| * files (the "Software"), to deal in the Software without |
| * restriction, including without limitation the rights to use, copy, |
| * modify, merge, publish, distribute, sublicense, and/or sell copies |
| * of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be |
| * included in all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
| * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS |
| * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN |
| * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| * SOFTWARE. |
| */ |
| |
| #include "avb_user_verity.h" |
| |
| /* Maximum allow length (in bytes) of a partition name, including |
| * ab_suffix. |
| */ |
| #define AVB_PART_NAME_MAX_SIZE 32 |
| |
| /* Loads the toplevel AvbVBMetaImageHeader from the slot denoted by |
| * |ab_suffix| into |vbmeta_image|. No validation, verification, or |
| * byteswapping is performed. |
| * |
| * If successful, |true| is returned and the partition it was loaded |
| * from is returned in |out_partition_name| and the offset on said |
| * partition is returned in |out_vbmeta_offset|. |
| */ |
| static bool load_top_level_vbmeta_header( |
| AvbOps* ops, |
| const char* ab_suffix, |
| uint8_t vbmeta_image[AVB_VBMETA_IMAGE_HEADER_SIZE], |
| char out_partition_name[AVB_PART_NAME_MAX_SIZE], |
| uint64_t* out_vbmeta_offset) { |
| uint64_t vbmeta_offset = 0; |
| size_t num_read; |
| bool ret = false; |
| AvbIOResult io_res; |
| |
| /* Construct full partition name. */ |
| if (!avb_str_concat(out_partition_name, |
| AVB_PART_NAME_MAX_SIZE, |
| "vbmeta", |
| 6, |
| ab_suffix, |
| avb_strlen(ab_suffix))) { |
| avb_error("Partition name and suffix does not fit.\n"); |
| goto out; |
| } |
| |
| /* Only read the header, not the entire struct. */ |
| io_res = ops->read_from_partition(ops, |
| out_partition_name, |
| vbmeta_offset, |
| AVB_VBMETA_IMAGE_HEADER_SIZE, |
| vbmeta_image, |
| &num_read); |
| if (io_res == AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION) { |
| AvbFooter footer; |
| |
| /* Try looking for the vbmeta struct in 'boot' via the footer. */ |
| if (!avb_str_concat(out_partition_name, |
| AVB_PART_NAME_MAX_SIZE, |
| "boot", |
| 4, |
| ab_suffix, |
| avb_strlen(ab_suffix))) { |
| avb_error("Partition name and suffix does not fit.\n"); |
| goto out; |
| } |
| io_res = ops->read_from_partition(ops, |
| out_partition_name, |
| -AVB_FOOTER_SIZE, |
| AVB_FOOTER_SIZE, |
| &footer, |
| &num_read); |
| if (io_res != AVB_IO_RESULT_OK) { |
| avb_errorv("Error loading footer from partition '", |
| out_partition_name, |
| "'\n", |
| NULL); |
| goto out; |
| } |
| |
| if (avb_memcmp(footer.magic, AVB_FOOTER_MAGIC, AVB_FOOTER_MAGIC_LEN) != 0) { |
| avb_errorv("Data from '", |
| out_partition_name, |
| "' does not look like a vbmeta footer.\n", |
| NULL); |
| goto out; |
| } |
| |
| vbmeta_offset = avb_be64toh(footer.vbmeta_offset); |
| io_res = ops->read_from_partition(ops, |
| out_partition_name, |
| vbmeta_offset, |
| AVB_VBMETA_IMAGE_HEADER_SIZE, |
| vbmeta_image, |
| &num_read); |
| } |
| |
| if (io_res != AVB_IO_RESULT_OK) { |
| avb_errorv( |
| "Error loading from partition '", out_partition_name, "'\n", NULL); |
| goto out; |
| } |
| |
| if (out_vbmeta_offset != NULL) { |
| *out_vbmeta_offset = vbmeta_offset; |
| } |
| |
| ret = true; |
| |
| out: |
| return ret; |
| } |
| |
| bool avb_user_verity_get(AvbOps* ops, |
| const char* ab_suffix, |
| bool* out_verity_enabled) { |
| uint8_t vbmeta_image[AVB_VBMETA_IMAGE_HEADER_SIZE]; /* 256 bytes. */ |
| char partition_name[AVB_PART_NAME_MAX_SIZE]; /* 32 bytes. */ |
| AvbVBMetaImageHeader* header; |
| uint32_t flags; |
| bool ret = false; |
| |
| if (!load_top_level_vbmeta_header( |
| ops, ab_suffix, vbmeta_image, partition_name, NULL)) { |
| goto out; |
| } |
| |
| if (avb_memcmp(vbmeta_image, AVB_MAGIC, AVB_MAGIC_LEN) != 0) { |
| avb_errorv("Data from '", |
| partition_name, |
| "' does not look like a vbmeta header.\n", |
| NULL); |
| goto out; |
| } |
| |
| /* Set/clear the HASHTREE_DISABLED bit, as requested. */ |
| header = (AvbVBMetaImageHeader*)vbmeta_image; |
| flags = avb_be32toh(header->flags); |
| |
| if (out_verity_enabled != NULL) { |
| *out_verity_enabled = !(flags & AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED); |
| } |
| |
| ret = true; |
| |
| out: |
| return ret; |
| } |
| |
| bool avb_user_verity_set(AvbOps* ops, |
| const char* ab_suffix, |
| bool enable_verity) { |
| uint8_t vbmeta_image[AVB_VBMETA_IMAGE_HEADER_SIZE]; /* 256 bytes. */ |
| char partition_name[AVB_PART_NAME_MAX_SIZE]; /* 32 bytes. */ |
| uint64_t vbmeta_offset; |
| AvbIOResult io_res; |
| AvbVBMetaImageHeader* header; |
| uint32_t flags; |
| bool ret = false; |
| |
| if (!load_top_level_vbmeta_header( |
| ops, ab_suffix, vbmeta_image, partition_name, &vbmeta_offset)) { |
| goto out; |
| } |
| |
| if (avb_memcmp(vbmeta_image, AVB_MAGIC, AVB_MAGIC_LEN) != 0) { |
| avb_errorv("Data from '", |
| partition_name, |
| "' does not look like a vbmeta header.\n", |
| NULL); |
| goto out; |
| } |
| |
| /* Set/clear the HASHTREE_DISABLED bit, as requested. */ |
| header = (AvbVBMetaImageHeader*)vbmeta_image; |
| flags = avb_be32toh(header->flags); |
| flags &= ~AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED; |
| if (!enable_verity) { |
| flags |= AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED; |
| } |
| header->flags = avb_htobe32(flags); |
| |
| /* Write the header. */ |
| io_res = ops->write_to_partition(ops, |
| partition_name, |
| vbmeta_offset, |
| AVB_VBMETA_IMAGE_HEADER_SIZE, |
| vbmeta_image); |
| if (io_res != AVB_IO_RESULT_OK) { |
| avb_errorv("Error writing to partition '", partition_name, "'\n", NULL); |
| goto out; |
| } |
| |
| ret = true; |
| |
| out: |
| return ret; |
| } |
